Folding knives are cutting instruments which generally have two positions. These include a closed, secure position with the cutting edge of the blade recessed within the handle, and an open position with the blade extended to expose the blade cutting edge. In the extended position the blade is generally "locked" in place to prevent the blade from inadvertently closing and potentially injuring the user of the blade.
The knife blade is generally locked in the extended position by either a latch mechanism located on the upper portion of the knife, i.e., near a user's thumb, or by the use of a leaf spring, or "linerlock". The linerlock is generally a rigid metallic plate which is interconnected to an interior surface of one of the scales of the handle and which has a biased metal stopping arm which extends into the recessed portion of the handle when the blade is extended open. An end portion of the linerlock stopping arm engages the rear end portion of the blade, thus preventing the blade from closing.
For safe and proper operation of a folding knife which utilizes a linerlock, the tolerance between the rear portion of the blade and the stopping arm portion of the linerlock is critical. If there is any significant gap between these two members, the blade will inadvertently move and slightly rotate even when the blade is in an extended, locked position. If the linerlock stopping arm is too long and there is no clearance between the rear end of the knife blade and the stopping arm, the linerlock will not properly engage the blade and the folding knife will not be capable of being properly locked in an extended open position.
To assure the proper tolerance between the linerlock and the rear end of the knife blade, a significant amount of time and expense is involved during the manufacturing of a folding knife which utilizes a linerlock. The majority of this time and expense is spent on the assembly line as the assembler attempts to properly align the knife blade rear end and the linerlock stopping arm in a position which assures a proper tolerance between the two components. This assembling procedure often requires the filing of the rear end of the blade, linerlock, or both with a steel file and the reassembly of the knife. Occasionally the knife must be disassembled numerous times before a proper fit is obtained, thus wasting valuable time and significantly adding to the cost of a folding knife which utilizes a linerlock locking mechanism.